Nitrogen use efficiency in Scotland: annual report 2024

Nitrogen Use Efficiency

In 2021, the whole economy Nitrogen Use Efficiency (NUE) figure was 25%. Although the whole economy figure is dominated by food production, this figure is lower than the NUE for food production due to the inclusion of sources such as transport which produce no useful nitrogen outputs. The NUE for all food production is 29%, with the figure for agriculture (28%) being very similar, given that agriculture dominates food production. The 28% figure for all of agriculture comprises two extremely different values for arable agriculture (65%) and livestock based agriculture (10%). Livestock based agriculture is inherently less nitrogen efficient than arable agriculture because only a small proportion of the ingested nitrogen by livestock ends up in useful nitrogen-containing produce (meat and milk, etc).

This year is the first year that the published dataset includes a time series of Nitrogen flows and Nitrogen Use Efficiencies, with the figures for previous years incorporating this year’s methodological improvements and the latest available data for these years. The methodological updates to SNBS have resulted in no change to the 2019 whole economy NUE and it remains at 25%. This was the only NUE to use the updated methodology Nitrogen flows, and changes to previous figures for the other NUE estimates is due to updates in the source datasets themselves.

The inherent uncertainties in the underlying data means that the SNBS may need to be revised in the future for purely technical reasons. Such revisions have the potential to affect all historic time periods referenced. Additionally, there will always be a variable level of uncertainty present due to the wide variety of data sources used, spread across a variety of administrative data, survey data and modelled data. The disparate methods will all have different levels of inherent uncertainty within them which means caution must always be taken when comparing between flows.